1. Field of the Invention
The present invention generally pertains to the optical imaging arts. Further, the present invention pertains to an improved system for reading optical indicia.
2. Description of Related Art
Devices have been developed that can read optical indicia without coming into physical contact with the particular optical indicia being read. Such reading or imaging devices are said to read in an “non-contact” fashion. Portable and non-portable such devices are known.
The reading devices capture an image of the indicia by sensing light-energy reflected from the indicia to the reading device. Such optical indicia readers illuminate the optical indicia by directing or scanning a light-energy source, such as a laser-generated or other type of light, across the surface of the indicia. Other types of reading devices are sometimes referred to as “instantaneous” readers. These readers generally illuminate the entire optical indicia at once and sense the reflected light energy with an area-type sensor.
All types of optical indicia readers, however, often capture an image of an optical indicia that turns out to be unreadable. The unreadability can be the result of several factors. Sometimes, for example, the reader is not accurately aimed and a sufficient portion of the optical indicia is not within the captured field of view. Sometimes the light-energy reflected back to the reader is not sufficient to permit a quality imaging. Other factors can also cause a captured field of view to be unreadable. As a final example, if the optical indicia is not located within the indicia reader's depth of field, if the indicia is too far from the reader for example, the captured image will be too out of focus to be readable.
Past indicia readers have incorporated some features calculated to increase reading performance. For example, some readers employ filtering technology in the time or spatial domain to remove some problems. Some readers have used a Fourier transformation to aid the reading process. If, however, a filtered or Fourier transformed image is not readable, the reading process must start over and a new image must be acquired.
What is needed is an improved indicia reading system that can read images that would have been unreadable with previous systems. Such a capability would improve efficiency since fewer optical indicia would have to be reread.